Composition and Temperature Monitoring of Molten Metal by a Combined LIBS-IR Thermometry System

The composition and temperature of molten metal in a furnace are important parameters in metallurgical industrial processing. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the in situ quantitative composition analysis of molten metal, and infrared radiation from molten metal can be used for temperature measurement. A near-infrared spectrometer was added to a LIBS system in this work. The LIBS signal and temperature information were recorded by the same optical system and optical fiber, and the temperature and the elemental content of the molten metal could be measured simultaneously. Molten carbon steel was used to verify the system performance. The measured temperature exhibited a good consistency with the temperature that was obtained by using a commercial pyrometer, with a relative root mean square error of 0.95%. The relative standard errors of Cr and Mn composition detection were lower than 10%. These results prove that it is possible to monitor composition and temperature in a molten metal process by a LIBS systems imultaneously.